1. Field of the Invention
This invention relates to computer pointing devices, in particular to such devices as used in portable computers.
2. Background and Prior Art
The presently used pointing devices like the mouse, the joystick or trackball use mechanical moving parts to translate the operator's hand movements into the movements of the computer cursor. However, in small and portable computers, like laptop computers, the space on the keyboard is inadequate for mounting of such devices which are of dimensions suitable for easy and unrestrained actuation. During operation, the operator's hand often covers the keyboard or an essential part of it and the pointing device is too small compared to the hand to precisely control the movement. In computers and control panels designed for operation under adverse conditions (water, dust, body liquids, etc.) it may be bard to make the system tight and protected. Other solutions include pointing devices to be used at the screen, like the light pen. Such a device has the disadvantage of being a separate additional device, sometimes hard to use on a tilted screen. Yet other pointing devices, such as digitizers, have been invented and are in use in precision digitalization. These include acoustic tablets, where two orthogonal microphones detect the relative position of a sound source (e.g. an electrical discharge at the tip of a pen-like device) based on the time elapsed for the sound to reach the respective microphones. In all cases known to us, the pointing device is movable or separate device, often requiring the possibility and space to lean the hand and arm against a fixed object in order to closely control the movements of the hand controlling the pointing device.